000
FGUS72 KRAH 171554
ESFRAH
NCC001-007-037-051-057-063-065-067-069-077-081-083-085-093-101-105-
123-125-127-135-145-151-153-163-165-167-181-183-185-191-195-241600-
Winter/Spring Flood Potential Outlook
National Weather Service Raleigh, NC
1155 AM EDT Sat Mar 17 2018
...THE CHANCE OF RIVER FLOODING OVER CENTRAL NC THIS SPRING IS NEAR
NORMAL...
Precipitation Summary
Rainfall over the past two weeks has been near to slightly below
normal across Central NC. There have been three precipitation events
so far this March, the wettest occurring on the 11th and 12th as
rain transitioned to snow, producing liquid equivalent amounts of
between half an inch and an inch and a half across the area. The
other two precipitation events produced around a half an inch to an
inch each.
See www.water.weather.gov for detailed rainfall analysis.
Precipitation and departure from normal:
Precipitation (inches) and departure from normal for the
water year beginning 1 October 2017
Month RDU GSO Fayetteville
------------------------------------------------------------------
October 4.29/ 1.04 3.03/-0.10 2.76/-0.45
November 1.28/-1.84 0.95/-2.16 0.54/-2.23
December 2.29/-0.78 1.60/-1.38 2.97/ 0.32
January 3.92/ 0.42 3.65/ 0.59 3.08/-0.22
February 1.70/-1.53 2.56/-0.40 1.62/-1.14
March (thru 3/15) 2.17/ 0.01 2.19/ 0.27 1.57/-0.13
Total precip 15.75/-2.68 13.98/-3.18 12.54/-3.85
Percent normal 85 81 77
---------------------------------------------------------------
Begin Actual Normal Departure Percent
date Pcpn Pcpn from norm of norm
RALEIGH-DURHAM INTERNATIONAL AIRPORT (RDU)
LAST 7 DAYS 03/07/2018 1.13 0.97 0.16 116%
LAST 14 DAYS 02/28/2018 2.24 1.87 0.37 120%
LAST 30 DAYS 02/12/2018 2.81 3.77 -0.96 75%
LAST 90 DAYS 12/14/2017 8.21 10.26 -2.05 80%
LAST 180 DAYS 09/15/2017 15.65 20.06 -4.41 78%
LAST 365 DAYS 03/14/2017 47.29 43.34 3.95 109%
PIEDMONT TRIAD INTERNATIONAL AIRPORT (GSO)
LAST 7 DAYS 03/07/2018 0.91 0.85 0.06 107%
LAST 14 DAYS 02/28/2018 2.20 1.66 0.54 133%
LAST 30 DAYS 02/12/2018 2.39 3.43 -1.04 70%
LAST 90 DAYS 12/14/2017 8.86 9.26 -0.40 96%
LAST 180 DAYS 09/15/2017 14.00 18.86 -4.86 74%
LAST 365 DAYS 03/14/2017 44.44 42.20 2.24 105%
FAYETTEVILLE AIRPORT (FAY)
LAST 7 DAYS 03/07/2018 0.67 0.74 -0.07 91%
LAST 14 DAYS 02/28/2018 1.63 1.45 0.18 112%
LAST 30 DAYS 02/12/2018 1.86 3.13 -1.27 59%
LAST 90 DAYS 12/14/2017 7.22 8.76 -1.54 82%
LAST 180 DAYS 09/15/2017 12.56 18.36 -5.80 68%
LAST 365 DAYS 03/14/2017 43.33 44.46 -1.13 97%
Streamflow and lake levels
Streamflow on unregulated streams and rivers across central NC
showed a trend of below to much-below normal across the northern
tier, while flows across the south were closer to normal for this
time of year. This was a modest improvement over February, which
exhibited uniformly below normal flows at month`s end.
See https://waterwatch.usgs.gov for additional details.
The major water supply and flood control reservoirs in central NC
are Falls Lake and B. Everett Jordan Lake, both operated by the U.S.
Army Corps of Engineers. Both of these lakes are currently within one
foot of their target elevations and are nearly steady. Current inflow
projections, which are based on conservative precipitation forecasts,
maintain near normal lake levels through mid Summer.
See www.epec.saw.usace.army.mil for additional details.
Short term forecast
The weather pattern favors progressive systems for the next two
weeks, and models suggest that several systems could potentially
provide modest to significant rainfall to the area. At this time,
none appear potent enough to produce a widespread 2-3 inches, which
current slightly-drier-than-normal hydrologic conditions would
require to produce flooding of significance on larger streams and
rivers.
Longer term precipitation outlook
We are currently in a weakening La Nina phase of the El
Nino/Southern Oscillation (ENSO) cycle, which is expected to
transition to ENSO-neutral over the next month or so. This is
the `warm` ENSO phase, which typically produces increased chances
of warmer-than-normal temperatures and less-than-normal
precipitation. This weakening climatological signal suggests
that the longer range chance of river flooding is normal to
slightly below normal.
Additional details and discussion may be found at the Climate
Prediction Center website: http://www.cpc.ncep.noaa.gov
In summary, current hydrologic conditions are slightly drier than
normal across central NC. There is a low chance for weather systems
in the near-term forecast that could produce precipitation
significant enough to cause minor river flooding through late March.
There are no climatological signals suggesting higher-probabilty
wet periods in the longer range outlook. As such, the chance of
flooding through early Spring is normal to slightly below normal.
The next scheduled Winter/Spring flood outlook will be issued
on March 30th.
For additional hydrologic or weather information, visit our website
at www.weather.gov/raleigh.
MLM